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High Battery Temperature Sensor Alarm and Inverter Fan running while in standby

WorldwideDave

Solar Enthusiast
Joined
Mar 5, 2024
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Not long ago I posted where discharging my CHINS 200Ah 12V LiFePO4 battery over 50 amps would cause the positive conductor to heat up. It was recommended that I do many things, but mostly to re-crimp my wires, and replace them with larger gauge. The thought was that the bad crimp was causing it to heat up, but to be safe, just went oversized on the wires as well. Which I did.

Things had been going well for the past 18 days until today. Two things happened out of the ordinary when I was away:

1.) The load that was scheduled to run at 7 AM for 7.5 hours stopped abruptly (has nothing to do with inverter - the load is a pool pump, and a low flow alarm stopped it)
2.) It was an abnormally hot day - 77 degrees it hit in Los Angeles where the solar setup is.

I had the system dialed in really good. The State of Charge each morning would be around 80 or 90%, the load would run for an hour or so until the MPPTs started to charge, then as the load was in use, the sun would both power the load and recharge the batteries to 100% SOC, then as the 'solar day' would end, the load would run for about another 30 minutes, and SOC would mellow down to 90% or so, losing 10% overnight to idle consumption, and repeat.

But when the load died, at both MPPTs were running, over 50 A of charging took place with no loads running.

I remember before I left for the afternoon I walked by the pool equipment, noticing it was off. I turned off the inverter with the on/standby button. I walked by again later, and I heard the inverter fans running (Giandel 2000W 12V). I thought it was strange...why would the inverter fans be running if the inverter is in standby mode and there are zero loads running on the inverter. When high amps run though a bus bar that an inverter in standby mode and two SCC and batteries are all connected to, does that cause an inverter to need to cool itself down?

I left for the day and about an hour later I received an alert on my phone that the battery temperature was over 129 degrees F / 54 degrees C.

I immediately called someone at the location, and had them open the PV disconnect for one of the MPPTs (Victron 100/20) that was charging at 19 amps or so at the time. For the Outback FM80 array, I believe it said it was at 49 amps at the time. So combined I was over 50 amps, possibly as high as 60 amps, probably for about an hour. That's when I got the VRM alert for battery temp.

So, back to square one with that setup.

I am going to go to 48V DIY battery after Jan 1, connected to Victron Quattro. I have built a shelf out of pressure treated wood in a new solar shed; the shelf it goes in is 3/4 CDX plywood (or similar). I have lights and outlets run, a panel ready to go. I can't wait to transition the pool setup off these 12V components.

Thanks for reading.

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Not long ago I posted where discharging my CHINS 200Ah 12V LiFePO4 battery over 50 amps would cause the positive conductor to heat up. It was recommended that I do many things, but mostly to re-crimp my wires, and replace them with larger gauge. The thought was that the bad crimp was causing it to heat up, but to be safe, just went oversized on the wires as well. Which I did.
Pointer to the previous discussion?

Once you redid the wiring, did the overheating problem go away?
 
It lowered the temperature by 20°C. But I’m fairly convinced that the BMS inside this battery is rated at 50 amp continuous and 100 amp maximum, but if you run it close to the maximum, it will continue to just heat up.
 
Pointer to the previous discussion?

Once you redid the wiring, did the overheating problem go away?
 
/*Once you redid the wiring, did the overheating problem go away?*/
So, no?
not completely, no. But it only gets warm on the positive terminal post, which is where the victron battery temp sensor is, and it got warm at this location before I replaced the conductors and lugs. It just doesn't seem to like going over 50 A for any duration of time if it is not charging at the same time from SCC or A/C charger. Example: At night, no sun, no charge connected, run load (pool pump & heater) and it heats up. But it is overheating less now than it was by 20 degrees.
 

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